Think Foursquare is just about bagging the mayorship to your local kebab house or getting a discount on your Starbucks coffee? Think again. The social location service wants you to shape up, and wish your friends a happy birthday.

Its VP of mobile and partnerships, Holger Luedorf, explained Foursquare's moral purpose in a social-networking panel this afternoon at Mobile World Congress.

"We are very interested in changing behaviour in a positive way," he said. "You can earn badges for running marathons, or doing other things that we think have a positive impact on people." A candles badge for wishing a friend happy birthday in a check-in, for example.

Sounds a bit... controlling? Don't worry, you can still earn a badge for being three sheets to the wind on a school night. But Lurdorf's comments were an interesting glimpse behind the scenes at Foursquare's desire to alter your habits.

"We're trying to help people explore the world around you," he continued. "The Holy Grail that we're working towards is that you have your phone in your pocket, you walk through a foreign city, and every time you want to see something or eat something, you pull out your phone and Foursquare gives you tips... It's like a much more personalised, socially enabled tour guide."

Luedorf said Foursquare currently has 6.5 million users, split 60-40 between the US and the rest of the world, with just under a million more joining every month.

He also said Foursquare is considering launching apps for tablets such as the BlackBerry PlayBook, and predicted that people are going to do an increasing amount of their social networking on their phones in the future.

"The mobile phone is inherently personal," he said. "Social media is going to drift towards mobile social media much more in the future. There's no doubt."